Along with increasing popularization of a surveillance system in commercial and civil applications, surveillance cameras have been widely applied in various fields for the purpose of guaranteeing public security. The majority of the surveillance cameras are in a 24-hour operation and have to output an image with stable quality regardless of the daytime or nighttime. Therefore, imaging in any high-end product of the surveillance cameras has to be characterized by a broad dynamic range, high reliability, etc. A predominant technology of a CCD camera is to capture an image by a multi-shutter method. However, the surveillance camera when used may suffer from a phenomenon of “color rolling” in case where a fluorescent lamp serves for illumination. As illustrated in FIG. 1, the difference between the frequency of the fluorescent lamp and that of the camera causes shifting of a sampling point of the camera, and consequently the amount of incident light sampled by the camera differs from the spectral distribution. Thus, an image processed by the camera is subject to color rolling. That is, the image may turn from white to blue, pink and back to white, and such a process will be repeated.
In an existing method for detecting color rolling, waveforms during color rolling have to be stored, and this requires a considerable memory and a significant effort of calculation, which may be inappropriate for hardware or for a microcontroller with a poor calculation capacity, and also lacks a good real time property.
Furthermore, a color rolling improvement function has been developed in the prior art to address the problem of color rolling. However, an image generated by a high-speed shutter might fade in color under certain conditions if the color rolling improvement function were enabled in the case of color rolling not being detected.